Gardenamide A Protects RGC-5 Cells from H₂O₂-Induced Oxidative Stress Insults by Activating PI3K/Akt/eNOS Signaling Pathway

• Published in: International journal of molecular sciences Vol. 16; no. 9; pp. 22350 - 22367
• Main Authors: Wang, Rikang, Peng, Lizhi, Zhao, Jiaqiang, Zhang, Laitao, Guo, Cuiping, Zheng, Wenhua, Chen, Heru
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.09.2015; MDPI
• Subjects: Animals; Antioxidants - pharmacology; Apoptosis; cell apoptosis; Cell Line; gardenamide A; Hydrogen Peroxide - toxicity; Iridoids - pharmacology; Kinases; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; neuroprotection; Neuroprotective Agents - pharmacology; neurotoxicity; Nitric Oxide Synthase Type III - metabolism; Oxidative Stress; Phosphatidylinositol 3-Kinases - metabolism; Proteins; Proto-Oncogene Proteins c-akt - metabolism; Rats; Retina; Retinal Ganglion Cells - drug effects; Retinal Ganglion Cells - metabolism; Rodents; Second Messenger Systems; cell apoptosis; gardenamide A; neurotoxicity; neuroprotection; oxidative stress
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms160922350

Gardenamide A (GA) protects the rat retinal ganglion (RGC-5) cells against cell apoptosis induced by H₂O₂. The protective effect of GA was completely abrogated by the specific phosphoinositide 3-kinase (PI3K) inhibitor LY294002, and the specific protein kinase B (Akt) inhibitor Akt VIII respectively, indicating that the protective mechanism of GA is mediated by the PI3K/Akt signaling pathway. The specific extracellular signal-regulated kinase (ERK1/2) inhibitor PD98059 could not block the neuroprotection of GA. GA attenuated the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) induced by H₂O₂. Western blotting showed that GA promoted the phosphorylation of ERK1/2, Akt and endothelial nitric oxide synthase (eNOS), respectively, and effectively reversed the H₂O₂-inhibited phosphorylation of these three proteins. LY294002 completely inhibited the GA-activated phosphorylation of Akt, while only partially inhibiting eNOS. This evidence implies that eNOS may be activated directly by GA. PD98059 attenuated only partially the GA-induced phosphorylation of ERK1/2 with/without the presence of H₂O₂, indicating that GA may activate ERK1/2 directly. All these results put together confirm that GA protects RGC-5 cells from H₂O₂ insults via the activation of PI3K/Akt/eNOS signaling pathway. Whether the ERK1/2 signaling pathway is involved requires further investigations.